Optimizing Industrial Refrigeration: How to Control this Energy-Intensive Area?

To reduce energy consumption, it is imperative to adopt certain best practices. The components of a refrigeration machine are calibrated for specific temperatures and pressures. Therefore, the control of the installation is essential. For example, in a system controlled by fixed setpoints, it is possible that it consumes more than it should, explains Yann Balem. The control of such installations can be complex because to be optimized, the operator will have to regularly modify the setpoint. In practice, installations can be observed that change their setpoint every three months. Ideally, a dynamic setpoint system would automatically optimize the installation’s consumption.

Finally, for optimizing industrial refrigeration, maintenance must be regularly performed: cleaning condensers and checking thermal insulation, purging non-condensables, etc.

The refrigeration cycle can be optimized. Several values must be observed for this: those of low and high pressure, as well as temperature differences at the condenser and evaporator levels. “The lower the low pressure, the more we consume,” recalls Sébastien Papouin. “Well adjusted, we can achieve a 2% optimization on compressors.”

Furthermore, to optimize industrial refrigeration, Dametis recommends using self-adaptive electronic expansion valves. This investment allows adjusting the refrigerant flow rate in the evaporator to perfectly match the refrigeration needs. Similarly, the implementation of variable speed drives on air condensers allows for Floating HP regulation, generating energy savings of up to 15%.

Another habit to adopt is the regulation of the distribution pumps for refrigerant fluids. “By controlling the pumps according to the needs, we save an average of 50% of the pump consumption,” adds Sébastien Papouin.

There are three main ways to recover heat rejected by a refrigeration system:

• The first is to recover heat from superheating at the compressor outlet. When the refrigerant is compressed by the compressor, its temperature increases significantly. The most often used technology is the implementation of a Gas/Water heat exchanger (called a Superheater), which allows heating water to high temperature (up to 70°C). The superheater allows recovering up to 10% of the total energy rejected by the refrigeration system.

• The second is to recover heat from the condensation of the refrigerant. The simplest way is to install a Gas/Water heat exchanger, which allows condensing the gas and heating water at medium temperature (from 30°C to 60°C depending on the characteristics of the refrigeration system). The advantage of the condenser is that up to 100% of the total energy rejected by the refrigeration system can be recovered.

• The last method is to recover heat from the compressor oil. Indeed, the compressor of a refrigeration system generates heat due to the friction and mechanical work involved in the compression process. This heat is usually dissipated by the compressor oil. Compressor oil heat recovery allows heating water to high temperature (up to 70°C). This technology is very interesting for screw compressors where we can recover up to 10% of the total power rejected by the refrigeration system.

This heat recovery can be used for a multitude of needs and can help reduce gas or electrical consumption in the factory. “The heat is first injected into the process needs: production of domestic hot water, heating of certain process elements, heating of boiler auxiliaries,” lists Sébastien. Afterward, it can be used to heat premises and, if there is excess, used for innovative processes such as cold or electricity production.

Heat recovery contributes to improving the overall energy efficiency of the refrigeration system by using heat that would otherwise be dissipated and therefore not valorized.

All these processes can reduce heating costs, improve installation performance, and strongly contribute to more sustainable environmental practices.

Up to 100% of the energy rejected by the refrigeration system can be recovered. The rejected power is equal to the sum of the cooling power and the electrical power of the compressors.

Dametis carries out projects ranging from design to final realization. Its experts can size the refrigeration installation according to the process needs to optimize your industrial refrigeration management. For example, Dametis accompanied alginate producers by installing a new refrigeration production where 100% of the heat is valorized in the process.

Then, Dametis takes care of setting up smart regulation to obtain constantly optimal operating setpoints for low-pressure, fan operation in the condenser, and distribution pumps.

These optimizations can be easily identified using the EMS MyDametis software. Additionally, the software automatically detects drifts to maintain performance over time.

Each solution is adapted to the specific issues of industries, with continuous improvement of performance and systematic cost reduction.